Electrical telephone



(No Model.)

F. DU PONT MARSTON. ELECTRICAL TELEPHONE. No. 3 0,905;

Patented Apr. 10, 1888;

0 "1 9 ,6 E T m x mm UNITED STATES PATENT ()FEICE.

F. DU PONT MARSTON, OF PHILADELPHIA, PENNSYLVANIA.

ELECTRICAL TELEPHONE.

I'SPECIPICATION forming part of Letters Patent No. 380,905, dated April 10, 11888.

Application filed April 15,1887. Serial No. 234,908. (No model.)

To aZZ whom, it may concern.-

Be it known that I, F. Du Pour MARsroN, a citizen of the United States, residing in the city and county of Philadelphia, State of Pennsylvania, have invented a new and useful Improvement in Electrical Telephones, of which the following specification, taken in connection with the accompanying drawings, is a full, clear, and exact description.

This invention is an improvement upon a telephone patented to me October 27, 1885, No. 329,327; and it consists in certain details,hereinafter enumerated, and particularly pointed out in the claims.

Figure 1 is a vertical section of my instru ment through the electrodes and sound-conducting tube. Fig. 2 is a perspective view of the diaphragm with its attached conductor. Fig. 3 is a side elevation of the instrument, showing all its connections. Fig. 4 is a crogssection ofa modified form of the gravity-electrode.

Similar letters of reference indicate corre* sponding parts in the several figures.

In my patent, No. 329,327, above referred to I have shown and described a contact-telephone with a horizontal diaphragm of glass carrying one electrode, the other electrode being sustained by gravity upon the first.

In the present application I have substituted for the glass diaphragm a diaphragm of carbon having a metal or wire conductor extending entirely around it and leading to one pole of the battery, the other electrode being a loose carbon rod or ball resting by gravity on the diaphragm and connected, as is usual, to the second pole of the battery through the primary of an induction-coil or in any other wellknown manner.

Referring, now, to the drawings, A represents the sustaining-base for carrying the working parts of the instrument.

J 1s a tube or passage for conducting the sound-waves to a point beneath the center of the diaphragm B.

Upon the diaphragm, which constitutes one electrode, rests the other electrode, F, consisting of a rod or ball of carbon free to slide into and out of a guide-tube, G, which latter is supported by fiat spring or springs D, attached contact.

to a rim, E, upon which the diaphragm rests. It will be observed that the diaphragm B has a metal band or Wire, G, extending entirely around it, so that sure electrical contact is had at all points 'of its circumference.

In the drawings I have shown the conductor G attached to the diaphragm by winding the closing the upper end of the tube G and excluding dirt and similar insulating material from the tube G. This tube G rests directly on the diaphragm in such manner that dirt cannot pass between it and the diaphragm from below.

In place of the solid electrode F (shown in Fig. l) I may use a hollow electrode of carbon or other material, with means for changing its weight, as shown in Fig. 4:, in which N is a cavity in the electrode, and 0 mercury or any weight, which may be increased or decreased at pleasure. I may also and sometimes do use a platinum point or tip on the gravity-electrode, as shown at B, Fig. 4, and such tips may be used with the electrode shown in Fig. 1, if desired.

L represents the door of the transmitter-box, and M a fiat spring located in the rear of the part A to cause said part to be held firmly against the door when closed.

K is a cushion of rubber, paper, felt, or analogous material for supporting the diaphragm, as is usual in the art. This cushion may be omitted, if desired.

The mode of operation is analogous to that of all well-known contact-telephones, and particularly those using gravity-electrodes, and need not be described.

I also provide a cap or plug, H, for- Having thus described niyinvention, what I a sound-conveying tube located beneath the claim as new, and desire to secure by Letters diaphragm, substantially as described. Patent, is- 3. In atelephone, a horizontal carbon dia- 15 1. A telephone with two carbon electrodes, phragm having a peripheral connection for 5 one only of which has a peripheral connection one conductor, a gravitating electrode being with a transmitting electrical generator, the sustained in a dust-tight guide-tube, substanother being held loosely in a guide, substantially as described.

tially as described. T 2. A telephone having a carbon diaphragm DU FONT MARSTOL' 10 with peripheral contact, as described, a loose Vitnesses:

gravitating electrode of smaller dimensions JOHN A. WIEDERsHEIM, than the diaphragm upon which it rests, and A. P. JENNINGS. 

